tji floor joists

[audwilly]

Joists look undersized, 9.5" with 2 1/2 inch cord spanning 17'. 2" poured concrete floor over. Any way to beef these up without posts and beams. Already 3/4" deflection in 6 months.
Thanks
Bill
Carpenter

 

[OkieDokie]

audwilly, I am hoping for your sake you had these tji's engineered. This way you can let the problem be a pain in his back. If not, call the manufacture and find out from them the recommendations to beef up there product. I recommend in this world we live in today to do a lot of CYA.

I sympathize with you on a issue like this. 22 years ago we were working a job were there was a lot more deflection on a floor than we were comfortable with also. I do not know what the deflection was, it was just to long ago. What I do remember is we had used 2x12's on 16" centers. I also remember inserting 2 more 2x12's between the floor joist and jacking the joist up in the center, tilting the new 2x12's up, beating then in to place and lowing the jacks. When I looked up afterwards and saw all those joist on about 5 1/2" centers I could not help but laugh. We then were able to go to the second floor and nail the decking down to the new joist. What a pain this was, even for the electricians.

It is a different world in construction today than it was 20 or 25 years ago. It just seems people are looking for a why or excuse to get something done a not pay for it.

 

[SperlingPE]

L/240 deflection for 17' is 0.85"
L/360 deflection is 0.57"

I can suggest putting more TJI's in to cut spacing between the existing TJI's. Or as OkieDokie stated, contact supplier for suggestions.

Downside: You are going to have to jack the existing joists up before adding more TJI's or strengthening the existing TJI's. This may cause some cracking in your concrete topping. This is a job for a contractor who has experience in doing this kind of work.

 

[geoffdale]

It may possible (and easier) to add a support beam cutting the effective span back down to something more reasonable, than adding joists in an area that may be quite congested.
What is the spacing of the joists?